#[derive(Debug)]
struct Point {
    x: i32,
    y: i32,
}
fn main() {
    // Box(智能指针) 可将数据在堆上分配 
    let a = Box::new(5);
    println!("a: {}", a);

    let p = Box::new(Point { x: 3, y: 4 });
    println!("point: {:?} ", p);

    // Box(智能指针)解引用
    let mut b = Box::new(25);
    *b += 5;
    println!("b: {}", b);
}
